Adjustable support to manipulate feed waveguide from rear of dish



Aug. 18, 1964 R, JENKINS 3,145,385

ADJUSTABLE SUPPORT TO MANIPULATE FEED WAVEGUIDE FROM REAR 0F DISH Filed Dec. 21. 1961 INVENTOR Biz/ti RJew/m s United States Patent of Delaware Filed Dec. 21, 1961, Ser. No. 161,000 1 Claim. (Cl. 343-481) This invention relates to antennas and more particularly it relates to antennas of the so-called illuminated reflector kind.

A principal object of the invention is to provide an improved manner of supporting the feed or illuminating system with precision relative to a dish shaped reflector which is to be illuminated by radiation, as for example microwaves.

A feature of the invention resides in a novel guy wire support for an antenna and feed line of the kind used for the illumination of reflectors.

Another feature relates to a supporting arrangement for a relatively heavy feed line such as a metallic wave guide and wave reverser assembly for illuminating a dish shaped main reflector, whereby the assembly can be placed in position from the rear of the main reflector while supporting the forward end of the assembly in a precise location with respect to the reflector, for example at the focus thereof.

A further feature relates to the novel organization, arrangement and relative location and interconnection of parts which cooperate to provide an improved feed linereflector antenna.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following detailed descriptions and the appended claim.

In the drawing which shows, by way of example, one preferred embodiment,

FIG. 1 is a plan view of an antenna embodying features of the invention;

FIG. 2 is a view similar to FIG. 1 but showing the manner of supporting the feed line assembly during its insertion or withdrawal with the main reflector;

FIG. 3 is a sectional view of FIG. 1 taken along the line 3-3 thereof;

FIG. 4 is an enlarged partly sectional view of the guy wire anchoring means relative to the feed line assembly;

FIG. 5 is a right hand end view of FIG. 4.

Certain fields of radio communication, for example microwave radar, require the use of a relatively large dish shaped metal reflector, for example parabolic or paraboloid, at whose focus is located an illumination device for illuminating the dish with the desired polarization and distribution of radiation. In order to couple the feed line or illuminating device to a transducer, for example, a microwave transmitter, it is usually necessary to employ a comparatively heavy and somewhat elongated metal wave guide. The wave guide carries at its forward end a horn or bell shaped arrangement for bending and reversing the waves toward the forward or front face of the reflector. In those antennas where the feed is from the rear of the main reflector, the feed line and wave reverser should, for a variety of reasons, be assembled or should be replaceable by an attendant without requiring him to be in front of the reflector. Usually such a feed line and reverser assembly are provided with impedance adjusting elements for matching the impedances of the various elements of the antenna system. For safety reason, at least, it is desirable to be able to assemble the feed line and reverser and to adjust the said elements from the rear of the main reflector. Furthermore, during assembly or replacement or adjustment of the feed line or reverser with respect to the reflector, the weight of the line or reverser render it diflicult to be inserted through the center of the reflector without an attendant being in front of the reflector to support the free end thereof during assembly or adjustment.

Accordingly, the present invention provides a novel supporting arrangement whereby the assembly, replacement or adjustment of the elements of the antenna can be effected entirely from the rear of the reflector and without danger of the heavy line assembly falling during its withdrawal or insertion through the disc.

Referring to FIG. 1, there is shown a typical antenna consisting of the dish shaped main reflector 10 which may be of parabolic or paraboloid shape and having a central opening 11 through which the feed and illumination assembly 12 is arranged to be passed. This latter assembly, when in final adjusted position, can be fastened to the rear face of the reflector 10 by a flange 13 and suitable bolts (not shown).

The feed and illumination assembly 12 comprises an elongated linear hollow metal wave guide 14, which at its forward end (that is, at the right hand end as seen in FIG. 1) carries a wave reverser unit 15 by means of which the waves which are transmitted through line 14, for example in the direction of the dotted arrow, are reversed so as to illuminate the concave surface of reflector 10. The invention is not limited to any particular kind of wave reverser, but a typical wave guide and reverser assembly may be that disclosed in the application of George B. Sleeper, Jr., and Bruce R. Jenkins, Serial Number 161,001 entitled Wave Guide Reflector Antenna, filed on even date herewith, now abandoned.

As is well known in the art, the mouth of the reverser should be located at or near the focus of the reflector 10. Therefore, when the reflector 10 is of large diameter, its focal length may be very great, for example as much as 144 inches. This requires a correspondingly long feed line 14, and the combined weight of that line and the reverser 15 is considerable. If it is attempted to pass such a heavy assembly through the opening 11, it is usually necessary for someone to support the free or forward end of the assembly while it is being adjusted to the proper position with respect to the reflector 10. I have found that it is possible to locate and support the assembly during its insertion and removal through the opening 11 with out an attendant being in front of the reflector 10. For this purpose, the closed end 16 of the reverser 15 has attached thereto by bolts 16 a metal plate 17 which has an integral boss 18. Fastened to the flat face of boss 18 is a guy wire anchoring ring 19 having an internal flat flange 20 which is fastened against the boss 18 by a bolt 21 and a flat washer 22 with an intervening lock washer 23. The ring 19 is coupled to the looped ends of three flexible guy wires 24, 25, 26. The loops 27 in each guy wire are formed by the reverse bending of each guy wire and with the reversed portion rigidly clamped and fastened against the length of the associated guy wire by a metal sleeve 28 which may be silver soldered thereto at 29 and 30. The loops 27 pass through respective openings in the flat flange 24) of the anchoring ring but are of somewhat larger diameter than the diameter of the cross section of the ring so as not to interfere with the movement of assembly 12 when it is being inserted or removed with respect to reflector 10. The opposite end of each guy wire is provided with a threaded portion 31 which passes through corresponding openings in the bent back lip 32 of reflector It). A pair of washers 33, 34 are fitted over the outwardly projecting end of the throat portion 31 and a tension spring 35 is located between the washers so that by turning the nuts 36, 37 the desired amount of tension or take up can be exerted on each guy wire individually.

As pointed out hereinabove, the reflector 10 has a central opening 11 which is of suflicient diameter to permit the assembly 12, as well as a portion of each guy wire, to be withdrawn toward the left as indicated in FIG. 2, so that the entire reverser portion 15, as well as the wave guide portion 14, are in the rear of the reflector 19. In this position the end of the assembly is supported by the guy wires and whatever adjustments are necessary can be made from the rear of the reflector.

When the adjustments have been made, the assembly 12 can be pushed to its forward position through the opening 11 and during this pushing operation the forward end of the assembly is also supported by the three guy wires. Since the guy wires are located at equi-angular spacings around the reflector 10, they automatically keep the assembly 12 in an axial position during its insertion into its final position. It will be understood, of course, that the nuts 36 and 37 have been previously adjusted so that when the assembly 12 is pushed to its forward position, the mouth of the reverser 15 is accurately located at the focus of the reflector 10.

While one particular embodiment has been disclosed herein, various changes and modifications may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

An antenna comprising a main reflector having a rim, a relatively long and relatively heavy feed line and wave reverser assembly for illuminating said reflector, a plurality of flexible guy wires, each said wire fastened at one end thereof to said rim by means of an individually adjustable coupler, each said coupler including means to adjust the tension and length of said guy Wire, said couplers being equidistantly spaced around said rim, said assembly including a ring at the outermost end thereof, means to removably affix said ring to said assembly, each of said guy wires being fastened at the other end thereof to said ring by means of a loop in said guy wire making a loose fit around said ring, and a central opening in said main reflector, said central opening being large enough to pass therethrough said assembly, said ring, said ring aifixing means, and at least part of said guy wires, whereby said assembly may be withdrawn and installed while being supported at all times and automatically properly positioned in regard to the focus of said reflector by said guy Wires, all operations being completely performable from said rear of said reflector.

References Cited in the file of this patent UNITED STATES PATENTS Lippitt et a1 Nov. 21, 1961 OTHER REFERENCES Inn-LA- 

